This disclosure relates to electrically conductive polymer foams and methods of manufacture thereof, as well as articles comprising the polymer foams.
Electrically conductive polymer foams are used in a wide variety of applications, including as electrical contacting devices, in sensors, and in applications requiring electromagnetic interference (EMI)/radio frequency interference (RFI) shielding and/or electrostatic dissipation. Exemplary materials capable of EMI/RFI shielding include metal foil or metallized fabric wrapped around non-conductive foam gaskets, and non-conductive gaskets coated with conductive materials. Materials suitable for electrostatic dissipation include conductive fillers loaded into various polymers, such as silicones, polyurethanes, and polyolefins. One drawback of using conductive fillers is that the addition of an amount of conductive filler sufficient to achieve high conductivity affects the compressibility and processability of the polymer. In addition, use of such high filler levels increases the cost of the polymer blend. Users are often forced to make a trade-off between the cost and the quality of the material. It has therefore been difficult to achieve high quality, conductive foams for use in EMI/RFI shielding
It would advantageous to provide polymer foams wherein the amount of added filler is minimized, while maintaining a suitable electrical conductivity. It would be a further advantage that the compressibility, processability, and other physical properties of the foam that are desired for a particular application not be significantly adversely affected.
There accordingly remains a need in the art for compositions and methods whereby foams can be provided with both electrical conductivity, compressibility and processability, particularly without significant adverse effect on one or more physical properties desired for a particular application.